(i) Technical Field of the Invention
This invention relates to an ink jet apparatus which ejects ink from a nozzle of an ink jet head to color a target object.
(ii) Description of the Related Art
In recent years, various methods for manufacturing organic EL (Electro Luminescence) display panels and panels for color filters of liquid crystal displays (LCD), by means of an ink jet apparatus have been introduced.
For instance, the Unexamined Patent Publication No. 2001-228820 discloses a method for manufacturing a color filter based on data representing manufacturing conditions, such as total ink volume supplied to a filter element, volume per ink drop ejected from a nozzle (ejected liquid amount), a main scanning frequency and a sub-scanning amount, provided beforehand per color filter of various types. This method simply requires modification of the data representing the manufacturing conditions when the user wishes to manufacture another type of color filter. Therefore, substantial reduction of the time required for initial setups was achieved.
In manufacturing of the organic EL display panels and panels for color filters of LCD by means of an ink jet apparatus, the most important parameters are the thickness of a film formed with ink, and then, the position where the film is formed. Accordingly, there has been a demand that the thickness of the film be arbitrarily adjusted even when the same type of panel is manufactured.
Generally, the thickness of the film formed with ink is uniquely defined depending on the number of ink drops ejected per unit area and volume per ink drop. Therefore, adjustment of the volume per ink drop ejected from a nozzle of an ink jet head is merely required in order to control the thickness of the film. In the ink jet apparatus, modification of the volume per ink drop from the nozzle is possible by increasing or decreasing parameters (such as driving voltage, driving frequency, waveform, for example) of a driving signal applied to the ink jet head. Accordingly, the thickness of film can be controlled by adjustment of the parameters of the driving signal.
However, in the aforementioned manufacturing method, manufacturing conditions are fixed pet color filter type. The manufacturing conditions, that is, parameters of the driving signal, are the same when the color filter of the same type is manufactured. Therefore, modification of the ink drop volume was not easy. The volume per ink drop can be changeable if a number of manufacturing conditions which differ in the ink drop volume are prepared for the same color filter, for example. However, it is not practical to prepare such a lot of data per manufacturing conditions since it requires enormous time and labor. If the data are not prepared, the user has to set the parameters. Thus a load to the user is heavy and the user operation becomes complex.
One object of the present invention is to provide an ink jet apparatus, a parameter determination method and a manufacturing method of organic EL display panel, that allow the user to modify parameters of a driving signal applied to an ink jet head with ease without provision of plural data per manufacturing conditions depending on desired ink drop volume. Another object of the present invention is to provide a parameter determination program for use in the ink jet apparatus, parameter determination method and manufacturing method of organic EL display panel.
In order to attain the above objects, an ink jet apparatus of the present invention is provided with an ink jet head having a nozzle for ejecting ink drops and capable of increasing or decreasing ink drop volume ejected from the nozzle depending on parameters of a driving signal applied. The ink jet apparatus comprises a volume input device for inputting unit volume representing total ink drop volume to be ejected within a unit area, a parameter determination device for determining the parameters of the driving signal to be applied to the ink jet head based on the unit volume inputted by the volume input device, and a reference volume calculation device for calculating reference volume representing total ink drop volume ejected within the unit area when a reference driving signal having reference parameters is applied to the ink jet head. The parameter determination device modifies the reference parameters so that a difference between the reference volume and the unit volume is equal to or lower than a predetermined threshold, and determines the modified reference parameters as the parameters of the driving signal to be applied to the ink jet head.
The ink jet apparatus constituted as above allows the user to modify the parameters of the driving signal applied to the ink jet head easily based on the desired unit volume inputted by the volume input device.
In this ink jet apparatus, the parameter determination device modifies the reference parameters, and compares the reference volume calculated by the reference volume calculation device based on the modified reference parameters with the unit volume inputted by the volume input device. The modification of the reference parameters, calculation of the reference volume by the reference volume calculation device, and comparison between the reference volume and the unit volume are repeated till the difference is equal to or lower than the predetermined threshold. In this way, the reference parameters that allow the difference to be equal to or lower than the predetermined threshold are easily obtained as a result of input of desired unit volume by the volume input device. The user can easily determine the parameters of the driving signal to be applied to the ink jet head which enables forming of the film with desired thickness even if he/she is not skilled in the operations of the ink jet apparatus.
The ink jet apparatus of the present invention further comprises an interval input device for inputting a unit interval representing an interval of the unit areas. The parameter determination device determines the parameters of the driving signal to be applied to the ink jet head based on the unit volume and the unit interval.
The ink jet apparatus constituted as above allows the parameter determination device to determine the parameters of the driving signal to be applied to the ink jet head based on not only the unit volume inputted by the volume input device but also the unit interval inputted by the interval input device.
The unit interval is a traveling distance from one unit area to another in a scanning direction of the ink jet head when the ink jet head scans a target object along its surface while ejecting ink drops. The parameter determination device determines the parameters which allow the unit volume to be ejected at a desired unit interval as the parameters of the driving signal to be applied to the ink jet head. Therefore, forming of the film with desired thickness is possible regardless of a pixel interval.
There is no limitation in the mechanism for modifying the reference parameters by the parameter determination device. However, it is preferable that the parameter determination device modifies the reference parameters by increasing or decreasing the reference parameters within a range of upper and lower limits preset to the reference parameters, for example.
With the ink jet apparatus constituted as such, modification of the reference parameters is possible by increasing or decreasing the reference parameters within the range of upper and lower limits preset to the reference parameters with which the ink jet head is operable in favorable condition.
It is preferable that the reference driving signal has n types of the reference parameters (1st to nth reference parameters), and that the parameter determination device increases or decreases one or more types of the reference parameters, among the n types of the reference parameters, within a range of upper and lower limits preset per type of the reference parameters.
Then, it is possible to increase or decrease one or more reference parameters for modification among the n types of the reference parameters of the driving signal, and determine the n types of the reference parameters including the modified reference parameter(s) as the parameters of the driving signal to be applied to the ink jet head.
In the present ink jet apparatus, the parameter determination device modifies the reference parameters by increasing or decreasing one or more types of the reference parameters. Then, based on the n types of the reference parameters including the modified reference parameters, the parameter determination device compares the reference volume calculated by the reference volume calculation device with the unit volume inputted by the volume input device. The modification of the reference parameters, calculation of the reference volume by the reference volume calculation device; and comparison between the reference volume and the unit volume are repeated until the difference is equal to or lower than the predetermined threshold. In this way, appropriate reference parameters that allow the difference to be equal to or lower than the predetermined threshold is obtained respectively as a result of input of desired unit volume by the volume input device. The user can reasonably determine the parameters of the driving signal to be applied to the ink jet head which enables forming of the film with desired thickness.
The parameter determination device may be designed to increase or decrease only one type of the reference parameters at a time or multiple types of the reference parameters simultaneously, when increasing or decreasing one or more types of the reference parameters. There is no limitation regarding the design when only one type of the reference parameters is increased or decreased at a time. However, it is preferable that the parameter determination device increases or decreases at least one of the reference parameters other than the ith reference parameter by a predetermined amount and then increases or decreases the ith reference parameter within the range of upper and lower limits, when the difference between the reference volume and the unit volume is more than the predetermined threshold even if the ith (inxe2x89xa6n) reference parameter is increased or decreased to its upper or lower limit.
With the ink jet apparatus constituted as above, the reference parameters which have much effect on reducing the difference between the reference volume and the unit volume to be equal to or lower than the threshold can be reasonably determined as the parameters of the driving signal to be applied to the ink jet head within the range of upper and lower limits with which the ink jet is operable in favorable condition.
It is preferable that the parameter determination device increases or decreases at least one of the reference; parameters other than the ith reference parameter by the predetermined amount and modifies one or both of the upper and lower limits for the ith reference parameter according to the amount increased or decreased, and then increases or decreases the ith reference parameter within the range of upper and lower limits.
Such an ink jet apparatus can modify, the upper or lower limit of the ith reference parameter according to the amount increased or decreased when any of the reference parameters other than the ith reference parameter are increased or decreased by the predetermined amount. Accordingly, the ith reference parameter can be increased or decreased within a different range of upper and lower limits before and after the increase or decrease of the any of the reference parameters other than the ith reference parameter.
There may be another design when one type of the reference parameters is increased or decreased at a time. That is, the parameter determination device may be designed to increase or decrease the i+1 parameters, when the difference between the reference volume and the unit volume is more than the predetermined threshold even if the ith (ixe2x89xa6n) parameter is increased or decreased to its upper or lower limit.
Consequently, even if the difference between the reference volume and the unit volume is not reduced to be equal to or lower than the threshold by the increase or decrease of the ith reference parameter, the parameter determination device can determine the reference parameters of the driving signal to be applied to the ink jet head which reduce the difference to be equal to or lower than the threshold by increasing or decreasing the i+1 reference parameter sequentially. In this case, prompt determination of desired parameters is possible since adjustments of the reference parameters are simple.
In the present ink jet apparatus, the difference between the reference volume and the unit volume cannot be reduced to be equal to or lower than the threshold if all the reference parameters are increased or decreased to their upper or lower limit before the difference between the reference volume and the unit volume is reduced to be equal to or lower than the threshold. Then, there is a fear that the parameters of the driving signal to be applied to the ink jet head cannot be determined.
To avoid the above, it is preferable that the parameter determination device determines the reference parameters modified to minimize the difference between the reference volume and the unit volume as the parameters of the driving signal to be applied to the ink jet head, when the reference parameters cannot be modified to reduce the difference between the reference volume and the unit volume to be equal to or lower than the predetermined threshold.
The parameter determination device of the ink jet apparatus determines at least a driving voltage which is a parameter of the driving signal to be applied to the ink jet head based on the unit volume.
The parameter determination device of the ink jet apparatus further determines at least a driving frequency which is a parameter of the driving signal based on the unit volume.
In the ink jet apparatus of the present invention, the volume input device inputs the unit volume for ink of organic EL (Electro Luminescence) material as the unit volume, and the reference volume calculation device calculates reference volume for ink of the organic EL material as the reference volume.
Another aspect of the present invention provides a method for manufacturing organic EL display panel with an ink jet head having a nozzle for ejecting ink drops and capable of increasing and decreasing ink drop volume ejected from the nozzle based on parameters of a driving signal applied. The method comprises steps of: inputting unit volume, representing total ink drop volume to be ejected within a unit area, of ink of the organic EL material; calculating reference volume, representing total ink drop volume ejected within the unit area, of ink of the organic EL material when a reference driving signal having reference parameters representing a basis is applied to the ink jet head; modifying the reference parameters so that a difference between the unit volume and the reference volume is equal to or lower than a predetermined threshold and determining the modified reference parameters as the parameters of the driving signal to be applied to the ink jet head; and driving the ink jet head with the driving signal having the parameters determined in the aforementioned parameter determining step.
Such a method is suitable for manufacturing organic EL display panel using the aforementioned ink jet apparatus.
The method for manufacturing organic EL display panel further comprises a step of inputting a unit interval representing an interval of the unit areas. In the parameter determining step, the parameters of the driving signal to be applied to the ink jet head are determined based on the unit volume and the unit interval.
In this method for manufacturing organic EL display panel, the reference parameters are modified by increasing or decreasing the reference parameters within a range of upper and lower limits preset to the reference parameters in the parameter determining step.
In this method, the reference driving signal has n types of the reference parameters (1st to nth reference parameters), and that one or more types of the reference parameters are increased or decreased within a range of upper and lower limits preset to each of the n types of the reference parameters in the parameter determining step.
It is preferable that at least one of the reference parameters other than the ith (ixe2x89xa6n) reference parameter is increased or decreased by a predetermined amount and then the ith reference parameter is increased or decreased within the range of upper and lower limits, when the difference between the reference volume and the unit volume is more than a predetermined threshold even if the ith reference parameter is increased or decreased to its upper or lower limit in the parameter determining step.
It is further preferable that at least one of the reference parameters other than the ith reference parameter is increased or decreased by a predetermined amount and one or both of the upper and lower limits of the ith reference parameter are changed according to the amount increased or decreased in the parameter determining step, and then the ith reference parameter is increased or decreased within the range of upper and lower limits.
In this method, the (i+1)th reference parameter is increased or decreased when the difference between the reference volume and the unit volume is more than the predetermined threshold even if the ith (ixe2x89xa6n) reference parameter is increased or decreased to its upper or lower limit in the parameter determining step.
Furthermore, the reference parameters modified to minimize the difference between the reference volume and the unit volume are determined as the parameters of the driving signal to be applied to the ink jet head, when the reference parameters cannot be modified so that the difference between the reference volume and the unit volume is equal to or lower than the predetermined threshold in the parameter determining step.
It is preferable that at least a driving voltage representing a parameter of the driving signal to be applied to the ink jet head is determined based on the unit volume in the parameter determining step.
It is further preferable that at least a driving frequency representing a parameter of the driving signal to be applied to the ink jet head is determined based on the unit volume in the parameter determining step.
The aforementioned method for manufacturing organic EL display panel comprises every step and characteristic corresponding to the devices and characteristics that the aforementioned ink jet apparatus may have. Therefore, it is suitable for manufacturing organic EL display panel using the aforementioned ink jet apparatus.
Another aspect of the present invention provides a method for determining parameters of a driving signal to be applied to an ink jet head of an ink jet apparatus. The ink jet head has a nozzle for ejecting ink drops and capable of increasing and decreasing ink drop volume ejected from the nozzle based on the parameters of the driving signal applied. In the method, reference volume representing total ink drop volume ejected within a unit area is calculated when a reference driving signal having reference parameters representing a basis is applied to the ink jet head. Furthermore, the reference parameters are modified so that a difference between the calculated reference volume and the unit volume representing total ink drop volume to be ejected within the unit area is equal to or lower than a predetermined threshold, and the modified parameters are determined as the parameters of the driving signal to be applied to the ink jet head.
Moreover, in this method, the reference volume for ink of organic EL material is calculated and the reference parameters are modified so that the difference between the calculated reference volume and the unit volume representing total ink drop volume of organic EL material to be ejected within the unit area is equal to or lower than the predetermined threshold and the modified parameters are determined as the parameters of the driving signal to be applied to the ink jet head.
An ink jet apparatus which determines parameters of a driving signal using the above method is designed to have the same functions as the aforementioned ink jet apparatus. Therefore, the same effects and advantages as the aforementioned ink jet apparatus can be achieved.
Another aspect of the present invention provides a parameter determination program that controls an ink jet apparatus. The ink jet apparatus is provided with an ink jet head having a nozzle for ejecting ink drops and capable of increasing and decreasing ink drop volume ejected from the nozzle based on the parameters of the driving signal applied. This program makes a computer system calculate reference volume representing total ink drop volume ejected within a unit area when a reference driving signal having reference parameters representing a basis is applied to the ink jet head, and then makes the computer system modify the reference parameters so that a difference between the reference volume calculated in the reference volume calculating step and unit volume representing total ink drop volume to be ejected within the unit area is equal to or lower than a predetermined threshold and to determine the modified reference parameters as the parameters of the driving signal to be applied to the ink jet head.
A computer system which determines parameters of a driving signal by the above parameter determination program can be a part of the aforementioned ink jet apparatus. The parameter determination program is suitable for performing the aforementioned method for manufacturing organic EL display panel using the computer system or the aforementioned ink jet apparatus.
The parameter determination program calculates the reference volume for ink of organic EL material, and modifies the reference parameters so that the difference between the calculated reference volume and the unit volume representing total ink drop volume for ink of organic EL material to be ejected within the unit area is equal to or lower than the predetermined threshold and determines the modified parameters as the parameters of the driving signal to be applied to the ink jet head.
A computer system which determines parameters of a driving signal by the above parameter determination program can be a part of the aforementioned ink jet apparatus.
The aforementioned parameter determination program is supplied to a computer system, ink jet apparatus, or user who utilizes the foregoing, via recording media such as a FD, CD-ROM, etc. and communication network such as radio and wireless networks, for example.
The computer system which executes the parameter determination program may be a computer system comprising the CPU of the aforementioned ink jet apparatus, or another computer system connected to the ink jet apparatus via radio and wireless networks for example.